Eagles GM Howie Roseman said at training camp on Tuesday that the team is in no rush to fill its three open spots on the 90-man roster. (AP)

There’s a pretty simple reason the Eagles’ roster is at 87 going into the first preseason game, three below the NFL preseason roster limit.

There just isn’t anybody out there worth signing.

Eagles general manager Howie Roseman said if the Eagles find a player they believe can make the Eagles better or increase competition at a specific position, they won’t hesitate to bring him in.

But for now, despite three open roster spots following season-ending injuries to Jason Phillips, Jeremy Maclin and Arrelious Benn -- all are on injured reserve with torn ACLs -- the Eagles are going with what they have.

“I think part of it is we want to make sure we’re evaluating guys that are here and practicing,” Roseman said while watching practice at the NovaCare Complex Thursday.

“When you’re so close to a game, to bring in somebody new and try to teach them then terminology and the system, it’s hard to get them functioning in that short a period of time.”

The Eagles open the 2013 preseason and the Chip Kelly era with a 7:30 p.m. game against the Patriots at the Linc Friday. The Eagles and Patriots spent the past few days practicing together at the NovaCare Complex.

Roseman asked a reporter to do some simple math: “Most teams have 90 guys and times that by 32 … What’s that number?”

Pause

“Is it 2,880?”

“Yeah.”

In other words … there are approximately 2,880 players currently on NFL rosters. Subtract three for the Eagles’ 87-man roster and you have 2,877.

So anybody the Eagles might sign at this point, would be – at best – the 2,878th-best player in the league.

Which explains why the Eagles are in no hurry to pick anybody up.

“You’re talking about a lot of players, and you don’t have the influx of guys that can come in off the street right now and do some of the things you’re looking for,” Roseman said.

“You keep your eyes open on the waiver wire and try to find some guys here who you think can upgrade the talent level at camp, who can create competition, and if not, you have enough guys on the roster.

“We’re used to having 80 guys on the roster for a long time, so give the guys who are here some reps and give them an opportunity to play.”

Specifically, the Eagles are very thin at wide receiver, with Maclin and Benn on injured reserve. Riley Cooper is back practicing and is expected to play Friday night after his leave of absence, but Damaris Johnson and Russell Shepard have both missed practice time this week with hamstring injuries.

The only receivers who haven’t missed a practice since camp began are DeSean Jackson, Jason Avant, Greg Salas, Will Murphy, Ifeanyi Momah and Nick Miller.

Roseman said instead of looking at it as being thin at wide out, he likes the fact that a lot of young guys will get long looks against the Patriots.

Notably among the young guys, Momah, Shepard and Salas have all done some good things and will get a ton of reps Friday evening.

“It’s important for us to get an evaluation of those guys and understand what they’re about,” he said. “We brought them here for a reason [and] we haven’t even had a game situation with any of them. Obviously some of them are flashing in practice and we’re excited to see them in more live situations.”

Finally, Roseman said bringing in camp bodies prior to a preseason game really doesn’t accomplish much anyway.

If a player isn’t prepared to play, you’re not going to get much out of him.

“You want to just make sure you’re giving those guys a fair chance when you bring them into camp,” he said. “If they don’t know what they’re doing, it’s hard to put them into a game, and then you’re not really helping.”